Principles of Operation

Wipers and Washers

Principles of Operation

Windshield Wiper Operation

The wiper system is activated by the multifunction switch. The multifunction switch is mounted to the Steering Column Control Module (SCCM). The SCCM commands the wiper motor to activate the appropriate wash, low, high and intermittent modes through a private Local Interconnect Network (LIN).

When the multifunction switch is in the HIGH position, the wiper motor also receives a ground signal which is hardwired directly through the SCCM (bypassing the logic within the module). This fail-safe circuit makes sure that the wipers function in HIGH speed mode in the event of a LIN communication failure.

Washer System

When the multifunction switch is placed in the WASH position, the SCCM sends the request to the windshield wiper motor through the LIN. The windshield wiper motor supplies voltage to the washer pump, which then directs washer fluid to the windshield.

Courtesy Wipe Feature

When the washer system is activated, the wipers cycle 3 times with washer fluid, followed by one final wipe a few seconds later to clear any remaining fluid that is dripping from the top of the windshield. This feature can be enabled/disabled through the message center. For information on enabling/disabling this feature, refer to the Owner's Literature.

Speed Dependent Wipers

If equipped, the speed dependent feature increases the frequency of wiping to compensate for the extra moisture that accumulates on the windshield as the vehicle speed increases. This feature activates when the multifunction switch is in any intermittent setting except the INT 1 position. As vehicle speed increases, the speed dependent feature gradually shortens the delay between wipes. The SCCM receives Vehicle Speed Sensor (VSS) information from the Body Control Module (BCM) through the High Speed Controller Area Network (HS-CAN). The SCCM sends the VSS information to the wiper motor through the LIN.

Rain Sensitive Wipers

If equipped, the rain sensitive wiper feature can be enabled/disabled at the message center. For information on enabling/disabling this feature, refer to the Owner's Literature.

When the rain sensitive wiper feature is enabled, it replaces the intermittent wiper feature. The rain sensor is located on the windshield near the rear view mirror. The rain sensor sends a message to the wiper motor through the LIN to activate the wipers. When the rain sensitive wiper system is active, the system activates the wipers and automatically adjusts the wiper speed when moisture is detected on the windshield. To activate the rain sensitive wiper feature, position the multifunction switch to 1 of the 5 auto/intermittent settings. The auto/intermittent position closest to OFF is the least sensitive to moisture. The highest auto/intermittent position is the most sensitive to moisture.

The rain sensor optically senses water on the windshield. An infrared beam of specific intensity lights a section of the windshield. The intensity of the reflected beam is measured and compared to the intensity of the transmitted beam. If there is water on the surface of the windshield, the beam distorts, reducing the intensity of the beam. If the beam is not reflected completely, it is interpreted as rain on the windshield and the wipers are started.

Wiper Activated Headlamps

If equipped with automatic headlamps, the SCCM sends a message to the BCM over the HS-CAN to illuminate the exterior lamps within 10 seconds of the wipers being activated by the multifunction switch when the headlamp control switch is in the AUTOLAMP position. The BCM continues to illuminate the exterior lamps for approximately 30 seconds after the wipers have been turned off.

If equipped with rain sensitive wipers (feature must be enabled through the message center) and the multifunction switch is in 1 of the 5 auto/intermittent settings, the SCCM sends a message to the BCM over the HS-CAN to illuminate the exterior lamps within 30 seconds of the wipers being activated by moisture detected on the windshield when the headlamp control switch is in the AUTOLAMP position. The BCM continues to illuminate the exterior lamps for approximately 60 seconds after the wipers have been deactivated (moisture no longer detected on the windshield).